SOME PECULIARITIES OF THE OLEFIN POLYMERIZATION OVER SUPPORTED VANADIUM CATALYSTS

The kinetics of ethylene and propylene polymerization on VCl3-based supported catalysts has been studied. Their specific activity was found to be very strongly related to the VCl3 content per support unit surface. The nature of the support affects the catalyst surface concentration at which the maximum activity is achieved. With supports (such as PE, PVC, aluminosilicate, SiO2) relatively weakly interacting with VCl3, the maximum is shifted toward higher VCl3 surface concentrations than those for strongly interacting ones [e.g., B, Fe(CO)(5)]. This effect may be connected with the ESR method evidenced distribution of the VCl3 phase on the support as clusters whose size increases with the increasing VCl3 quantity. The VCl3 surface concentration and the support itself affect also the stability of active centres in ethylene and propylene polymerization.